Mozilla security researcher moz_bug_r_a4 reported that XrayWrappers can be bypassed to call content-defined toString and valueOf methods through DefaultValue. This can lead to unexpected behavior when privileged code acts on the incorrect values.

In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products.



External Reference:

http://www.mozilla.org/security/announce/2013/mfsa2013-59.html


Acknowledgements:

Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges moz_bug_r_a4 as the original reporter.